1. Field of the Invention
The present invention relates to a III-nitride semiconductor electronic device, and a method of fabricating a III-nitride semiconductor electronic device.
2. Related Background Art
Patent Literature 1 discloses a heterojunction type field effect transistor. This transistor has an AlGaN channel layer and an AlGaN barrier layer. Source/drain electrodes are formed with use of ion implantation of silicon and are made of Ti/Al.
Patent Literature 2 discloses a junction of channel layer/barrier layer. The channel layer is made of AlGaN. In a high electron mobility transistor including the AlGaN channel layer with an Al composition of not less than 0.16, ohmic electrodes of Ti/Al are formed using impurity doping by ion implantation. Its impurity concentration is not less than 1×1018 cm−3.
Non Patent Literature 1 discloses a high electron mobility transistor which uses an AlGaN channel layer and an AlGaN barrier layer. Silicon ions are implanted with the acceleration energy of 50 KeV and at the dose concentration of 1×1015 cm−2 into junction areas which are connected to the source electrode and the drain electrode, and Ti/Al electrodes are formed on the heavily-doped regions.
Non Patent Literature 2 discloses a high electron mobility transistor produced by an electron beam method. This high electron mobility transistor has an AlGaN channel layer with an Al composition of 0.06, and its ohmic electrodes are made of Ti/Al/Ni/Au.
Non Patent Literature 3 discloses an AlGaN/GaN high electron mobility transistor. In this AlGaN/GaN transistor, Id-max (maximum drain current) decreases with increase in temperature.    Patent Literature 1: Japanese Patent Application Laid-open No. 2008-243881    Patent Literature 2: Japanese Patent Application Laid-open No. 2009-049358    Non Patent Literature 1: Applied Physics Express 1, (2008) 011101, Takuma Nanjo, et al., “First Operation of AlGaN Channel High Electron Mobility Transistors.”    Non Patent Literature 2: Japanese Journal of Applied Physics, Vol. 47, No. 5, 2008, pp-3359-3361, Ajay RAMAN, et al., “AlGaN Channel High Electron Mobility Transistors: Device Performance and Power-Switching Figure of Merit.”    Non Patent Literature 3: APPLIED PHYSICS LETTERS, VOL. 80, No. 12, 25 Mar. 2002, pp-2186-2188, S. Arulkumaran, et al., “High Temperature Effects of AlGaN/GaN high-electron Mobility Transistors on sapphire and semi-insulating SiC substrates”